一、现象描述
启动elasticsearch时报如下错误：
- RuntimeException[Java version: 1.7.0_40 suffers from critical bug https://bugs.openjdk.java.net/browse/JDK-8024830 which can cause data corruption.Please upgrade the JVM, see http://www.elastic.co/guide/en/elasticsearch/reference/current/_installation.html for current recommendations.If you absolutely cannot upgrade, please add -XX:-UseSuperWord to the JVM_OPTS environment variable.
Upgrading is preferred, this workaround will result in degraded performance.]
二、可能原因
原因一：linux系统存在多版本的jdk(包括openjdk)，导致elasticsearch识别出错；
原因二：jdk的版本不够新；
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经排查发现系统已安装jdk1.7.0_79,但是usr/bin/java的软链接指向了/etc/alternatives/java，而/etc/alternatives/java却又指向/usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java，导致elasticsearch识别的是jdk1.7.0版本的jdk。
三、解决方法：
方法一：
ln -s /usr/java/jdk1.7.0_79/bin/java /usr/bin/java
方法二(建议)：
//添加jdk1.7.0_79的link值
update-alternatives --install /usr/bin/java java /usr/java/jdk1.7.0_79/bin/java 999999
//选择一个link值：即选择一个版本的java
update-alternatives --config java